Projection optical system, exposure apparatus, and method of manufacturing device

Abstract

This invention is a projection optical system which includes a plurality of lens groups and projects an image of a first object onto a second object. A bottom lens group of the plurality of lens groups which is positioned nearest to the second object is made of an isotropic crystal material having a refractive index of 1.6 or more and has a positive focal length. A curvature radius R (mm) of a surface of the bottom lens group which is located on the first object side and a center thickness d (mm) of the bottom lens group satisfy 3.0>R/d>1.6 and d<60.

1. A projection optical system which includes a plurality of lens groups and projects an image of a first object onto a second object,
 wherein a bottom lens group of the plurality of lens groups which is positioned nearest to the second object comprises a cemented lens obtained by cementing not less than four lenses made of an isotropic crystal material having a refractive index of not less than 1.6 and has a positive focal length, and 
 wherein a curvature radius R (mm) of a surface of the bottom lens group which is located on the first object side and a total center thickness d (mm) of the cemented lens satisfy 3.0>R/d>1.6 and d<60. 
 
     
     
       2. A system according to  claim 1 , wherein a <1, 1, 1> crystal axis of an isotropic crystal material for at least two lenses of lenses constituting the cemented lens is oriented in a direction of an optical axis, and a <1, 0, 0> crystal axis of an isotropic material for at least two lenses of the lenses constituting the cemented lens is oriented in the direction of the optical axis. 
     
     
       3. An exposure apparatus which comprises a projection optical system configured to include a plurality of lens groups and to project an image of an original onto a substrate and exposes the substrate to light via the original and the projection optical system,
 wherein a bottom lens group of the plurality of lens groups which is positioned nearest to the second object comprises a cemented lens obtained by cementing not less than four lenses made of an isotropic crystal material having a refractive index of not less than 1.6 and has a positive focal length, and 
 wherein a curvature radius R (mm) of a surface of the bottom lens group which is located on the first object side and a total center thickness d (mm) of the cemented lens satisfy 3.0>R/d>1.6 and d<60. 
 
     
     
       4. An apparatus according to  claim 3 , wherein a gap between the bottom lens group and the substrate is filled with a liquid. 
     
     
       5. A method of manufacturing a device, the method comprising:
 exposing a substrate by using an exposure apparatus; 
 developing the exposed substrate; and 
 processing the developed substrate, 
 wherein the exposure apparatus comprises a projection optical system configured to include a plurality of lens groups and to project an image of an original onto a substrate and expose the substrate to light via the original and the projection optical system, 
 wherein a bottom lens group of the plurality of lens groups which is positioned nearest to the second object comprises a cemented lens obtained by cementing not less than four lenses made of an isotropic crystal material having a refractive index of not less than 1.6 and has a positive focal length, and 
 wherein a curvature radius R (mm) of a surface of the bottom lens group which is located on the first object side and a total center thickness d (mm) of the cemented lens satisfy 3.0>R/d>1.6 and d<60.